Princeton builds a semiconductor reprogrammable with light

Saien Xie holds up a square of material at Princeton Engineering: 1 inch on each side, yet only a few molecules thick. The team has created a semiconductor that can be programmed, erased and reprogrammed with light—a departure from devices whose electrical behavior is largely fixed once they leave the factory.

The mechanism is molecular. Princeton researchers combined an ultrathin semiconductor with light-responsive molecules that change structure under different wavelengths. Those changes modify the semiconductor’s electronic properties, including its conductivity and optical response, so the material can be tuned gradually rather than treated as a simple on-off switch.

That flexibility matters because conventional semiconductor progress has largely come from making devices smaller, a path the researchers say is approaching physical limits. Their alternative is to make the material itself adaptable. The group has already built arrays of programmable electronic switches from the square sample, and is working to connect them into a circuit.

And so what, concretely? If the approach can move beyond the laboratory, the same kind of reconfigurable material could support more adaptable sensors, optoelectronic devices and computing technologies. A device might have properties changed after fabrication rather than being locked into one function during manufacturing.

For now, that destination remains a research goal. Saien Xie and Jaehoon Ji’s team has demonstrated the material and switch arrays, but the next circuit-level step is still under development. The findings were reported in Science Advances.